36 



THE POPULAR SCIENCE MONTHLY 



2. Reflex Motions = 



Relatively Simple, Automatic Re- 

 sponses. 



3. Organic Memory = 



Results of Previous Experience 

 registered in General Proto- 

 plasm. 



4. Adaptive Besponses = 



Results of Elimination of Useless 

 Responses through Trial and 

 Error. 



5. Varied Besponses 



Dependent upon Conflicting Stim- 

 uli and Physiological States. 



6. Identity = 



Continuity of Individual Organi- 

 zation. 



2. Instincts (Inherited) , Habits {Ac- 



quired) = 

 Complex Reflexes, involving Nerve 

 Centers. 



3. Associative Memory = 



Results of Experience registered in 

 Nerve Centers and Association 

 Tracts. 



4. Intelligence, Beason = 



Results of Trial and Error plus 

 Associative Memory, i. e. Ex- 

 perience. 



5. Inhibition, Choice, Will 

 Dependent upon Associative Mem- 

 ory, Intelligence, Reason. 



6. Consciousness = 



Continuity of Memory, Intelligence, 

 Reason, Will. 



Factors of Development 



These are some of the facts of development — a very incomplete re- 

 sume of some of the stages through which a human being passes in the 

 course of his development from the germ. What are the factors of de- 

 velopment ? By what processes is it possible to derive from a relatively 

 simple germ cell the complexities of an adult animal? How can mind 

 and consciousness develop out of the relatively simple psychical elements 

 of the germ? These are some of the great problems of development — 

 the greatest and most far-reaching theme which has ever occupied the 

 minds of men. 



Preformation. — When the mind is once lost in the mystery of this 

 ever recurring miracle it is not surprising to find that there have been 

 those who have refused to believe it possible and who have practically 

 denied development altogether. The old doctrine of " evolution " as it 

 was called by the scientists of the eighteenth century, or of preformation 

 as we know it to-day held that all the organs or parts of the adult were 

 present in the germ in a minute and transparent condition as the leaves 

 and stem are present in a bud, or as the shoot and root of the little plant 

 are present in the seed. 3 In the case of animals it was generally impos- 

 sible to see the parts of the future animal in the germ, but this was sup- 

 posed to be due to the smaller size of the parts and to their greater trans- 

 parency, and with poor microscopes and good imagination some observ- 

 ers thought they could see the little animals in the egg or sperm, and 

 even the little man, or " homunculus," was described and figured as 

 folded up in one or the other of the sex cells. 



* The little plant in the seed is itself the product of the development of a 

 6ingle cell, the ovule, in which no trace of a plant is present, but of course this 

 fact was not known until after careful microscopical studies had been made of 

 the earliest stages of development. 



